75 Mineralogy, Geochemistry, Petrology, and Volcanology Student Session (Posters)

GSA’s MGPV student representatives invite the division’s student population to present their research (oral or poster). We encourage abstracts from any subdiscipline within our respective fields with hopes of stimulating a multi-disciplinary, early career researcher (ECR) community within MGPV.

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Evaluating Heterogeneous Characteristics Across the Medicine Park Granite, Wichita Mountains, Southern Oklahoma

Paper number: 75-10
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Within the Wichita Mountains of Southern Oklahoma are exposures of Cambrian plutons and associated intrusions known as the Wichita Granite Group. The Mount Scott Intrusive Suite is a subset comprised of four units: the Mount Scott, Rush Lake, Saddle Mountain, and the Medicine Park Granites. The Medicine Park Granite is unique, with a finer-granophyric matrix, few phenocrysts, and largely unresolvable mafic minerals, presenting an appearance similar to a rhyolite in hand sample. This study examines the chemical and physical characteristics of the Medicine Park Granite across its extent to characterize its heterogeneity, especially in contact zones.

Preliminary investigation used previously collected samples with their thin sections and whole-rock compositions. The thin sections were digitized on a flatbed scanner at 6400 dpi in plane and cross-polarized light. These were also characterized by SEM-EDS for their microstructure and determine phenocrysts and surrounding matrix composition. The Medicine Park Granite appears to be dominated by a distinctively fine perthitic granophyre with sparse phenocrysts of Mc-rich perthite and Qz. The perthite phenocrysts and granophyre are separated by a 50 μm Mc rim. Biotite is its dominant mafic silicate, but only as trace concentrations as submillimeter grains, some within small clusters of FeTi-Oxides+Ttn+Zrn ±Apt. Ttn appears in close association with FeTi-Oxides. CL revealed significant zoning in quartz and zircon grains. 

Thus far, differences among samples are subtle. Future research will collect additional field samples for thin sectioning, whole-rock and phase geochemistry to map zones of differing characteristics of the Medicine Park Granite.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412967

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